1. Field
The disclosed method of making and article of manufacture relates generally to electrode apparatuses, and particularly to electrode apparatuses adapted for use in an energy storage device, such as for example in a capacitor or a battery.
2. Related Art
Energy storage is a major issue in the modern technological marketplace. Efficient delivery of energy (or power) is a related major issue. Batteries have historically played a major role in energy storage solutions. A battery is a device that stores electric charge for use as a power source. The charging process is based on a chemical reaction that takes place between an electrolyte and two electrodes called an anode and cathode. The capacity to store electric charge is a function of the surface area of these electrodes and the particular electrolyte used. Common types of batteries include sealed lead acid (“SLA”) batteries, nickel-cadmium (“Ni—Cd”) batteries, and litium-ion (“Li-Ion”) batteries. SLA batteries can hold a charge for up to three years and are generally used to provide backup power during emergencies. Ni—Cd batteries provide a fast, even energy discharge and are most often used to power appliances and audio and video equipment. Li-Ion batteries have the highest energy storage capacity (generally twice the capacity of Ni—Cd batteries) and are used to power portable computers, cellular phones, and digital cameras to name a few applications.
Another type of battery known as a double-layer capacitor stores energy based on a microscopic charge separation that takes place at an electrical-chemical interface between an electrode and electrolyte, The capacitor is charged by a primary energy source and then discharged when connected to a device to be powered, generally referred to as a load. The charging and discharging process is repeatable; that is, after discharging takes place through the load the capacitor may be recharged by connecting its electrodes to the primary energy source. Double-layer capacitors have been used to power a myriad of bulk electronic devices including radios, motors, and the like.
Double layer capacitors, also referred to as electrochemical double layer capacitors, are energy storage devices that are able to store more energy per unit weight and unit volume than traditional capacitors. Additionally, they can typically deliver the stored energy at a higher power rating than rechargeable batteries.
There is a continuing need for improved double layer capacitor design. Such improved double layer capacitors need to deliver large amounts of useful energy at a very high power output and energy density ratings within a relatively short period of time. Such improved double layer capacitors should also have a relatively low electrode equivalent series resistance (ESR) and yet be capable of yielding a relatively high operating voltage.
An ESR rating for a capacitor is a rating of quality. A theoretically perfect capacitor would have an ESR of zero. However, all real capacitors have some amount of ESR. Hence, a real-world challenge for capacitor designers is minimizing ESR. ESR is modeled like a resistor in series with a capacitor. Capacitor designs that appear optimally functional in theory, can fail when manufactured due to ESR. Increasingly, modern electronic designs rely on low ESR capacitors to function optimally in a real-world environment.
Double layer capacitors consist of two porous electrodes that are isolated from electrical contact by a porous separator. Both the separator and the electrodes are impregnated with an electrolytic solution. This allows ionic current to flow between the electrodes through the separator at the same time that the separator prevents an electrical or electronic (as opposed to ionic) current from shorting the cell. Coupled to the back of each of the active electrodes is a current collecting element. One purpose of the current collecting element is to reduce ohmic losses in the double layer capacitor.
Drying time and electrolytic solution impregnation efficiency of an ultracapacitor electrode are key processes during ultracapacitor manufacturing. Both processes are crucial for longer lifetime and reduced manufacturing cost of ultracapacitor products
Therefore, the present teachings provide a method of making and article of manufacture for an energy storage apparatus, which reduces electrode drying time and improves electrolytic solution impregnation efficiency during a manufacturing process, while simultaneously reducing the cost associated with such manufacture and expediting the process.